The shape of a cell and the mechanical properties of its plasma membrane are determined by a meshwork of fibrous proteins called what?

Cell Cortex

Explanation:

This cell cortex, can also be reffered to as the actin cortex or actomyosin cortex, which is a specialized layer of cytoplasmic proteins on the inner face of the cell membrane.

this cell cortex functions as a modulator of membrane behavior and cell surface properties.